Hashcat rules generate duplicates

[Wolfdale]

I'm using the following command to redirect the words generated by hashcat with the best64 rule to a file. The file 'test' contains only the word test.

hashcat -r /usr/share/hashcat/rules/best64.rule test --stdout >> best64.txt

The command creates a file with 201 words.

wc -l best64.txt
201

But it contains duplicates!

..
t3st
tet
te
tes
tes
te
t
tt
..
..

I did
sort -u best64.txt | wc -l
188

So it created 13 duplicates!

i'm probably doing something wrong, anyone able to help? Thanks guys!